When biologically available, heavy metals leaching from soil, water or waste, as well as those released into the air, are detrimental to all living beings. Permissible levels of heavy metal pollution are regulated by the local, state and federal authorities. The important sets of federal regulations are the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), which governs the Superfund program. One of the earliest remediation methods, the removal and hauling of heavy metal contained waste and soil to a landfill, while still in use, is more frequently being viewed by the public as unacceptable. New regulations and continued desire to find better and/or inexpensive environmental pollution control, prevention and remediation techniques have driven potential hazardous and/or toxic waste generators toward new technologies. Encapsulation of heavy metal-containing waste in portland cement, for example, though meeting the letter of the environmental law, does not meet the spirit of the law when the encapsulated waste is exposed to rain. Under those circumstances, heavy metals go into solution and become biologically available. Permanent stabilization by forming geochemically stable compounds of heavy metals is by far the best solution to this challenge. Certain industrial processes may also release acid gases which need to be removed. Often pH control of the contaminated matrix is also required.
Numerous methods, mostly multi-step and sequential-step, have been utilized to prevent the leaching of hazardous heavy metals in solid, semi-solid, liquid and/or gaseous complex matrices so that the waste is rendered suitable for disposal in a sanitary landfill. There has, however, been no suggestion to use sulfonated calcium aluminum magnesium phosphates, hydroboracite or scrubber magnesium product (magnesium sulfite) for the purpose of providing heavy metal stabilization, together with the additional benefits of acid gas removal and pH control, to contaminated or treated matrices in a one-step method or single-product composition. U.S. Pat. No. 4,671,882, Douglas et al., issued June, 1987, discloses a multi-step process for heavy metal stabilization. Douglas does not prefer to use limestone because he believes that the use of limestone results in the production of carbon dioxide gas when added to acid solution and such gas would adversely affect the pH increasing step essential to his multi-step heavy metal stabilization process. Both U.S. Pat. Nos. 4,889,640 and 5,037,479, Stanforth, suggest that limestone is not effective in the disclosed heavy metal stabilization processes because it is a non-reactive form of calcium and/or magnesium carbonate. The above-mentioned patents do not suggest any products or processes for acid gas removal.